Dosing apparatus for detergent paste

ABSTRACT

The invention relates to a dosing apparatus for pastelike substances and mixtures thereof with a solvent by means of an injector, comprising an integrated shutoff device. The apparatus contains a detection device which detects the amount of paste according to conductimetry. The shutoff device is a dual piston valve closing an opening between the paste supply tube and an injector suction chamber as well as an opening between the solvent supply tube and an injector pre-chamber. The invention also relates to a method for dosing pastelike substances and the mixtures thereof with a solvent by means of such a device. By opening a shut-off device in a supply tube for a pressurized solvent, a dual piston valve moves against an opposing force. This releases a connection between a paste supply tube and an injection suction chamber, followed by a connection between the solvent supply tube and the injector pre-chamber. The paste is suctioned by an injector operating according to the hydraulic pump principle and mixed with released solvent. The mixture is injected into a measuring section wherein a conductimetry device measures the amount of paste dissolved in the mixture. The shut-off device is closed when the required dose of paste is obtained, whereupon the circuit which was previously in an open position is shifted in reverse order to a closed position.

RELATED APPLICATIONS

This Application is related to co-pending application U.S. Ser. No.09/284,296 for “A POT WITH A FLEXIBLE STORAGE BARREL AND FOLLOW-UPPLATE”, filed May 10, 1999, and U.S. Pat. No. 6,149,034 for “PASTEDISPENSER”, issued Nov. 21, 2000.

BACKGROUND

1.0 Field of the Invention

This invention relates generally to viscous product dispensers, and moreparticularly to an apparatus and a process for dosing paste-formsubstances and for mixing them with a solvent by an injector with anintegrated shutoff member.

2.0 Discussion of Related Art

Liquid to paste-form detergents are known in large numbers. They aregenerally formulated to meet domestic requirements, i.e. they areexpected to be sufficiently liquid so that they can be poured out andmeasured/dosed without difficulty. Since, in addition, they are expectedto be stable in storage over a relatively broad temperature range, theuse of organic solvents and/or hydrotropic additives cannot normally beavoided. However, such additives do not contribute to the actual washingprocess, are comparatively expensive and, in addition, take up packagingspace and transportation and storage capacity. The presence ofinflammable solvents is particularly troublesome and necessitatesadditional safety precautions because of the relatively high consumptionof detergents in laundries. As a result, detergent concentrates of thetype mentioned can only be used to a limited extent, if at all, inlaundries.

Accordingly, powder-form detergents are mainly used in laundries. Sincethe exact dosing of powder-form detergents is problematical orlabor-intensive, particularly in large and extensively automatedlaundries, the detergents are mostly stored and dispensed inpredissolved form as stock liquors, i.e. a water-based concentrate isprepared and delivered to the individual points of consumption. However,the detergents typically used in laundries contain comparatively highlevels of washing alkalis which are only soluble to a limited extent incold water and, in addition, lead to so-called salting-out effects. Theypromote phase separation with the result that the organic components,more especially the nonionic surfactants and soaps, separate and creamup. Accordingly, the concentrates have to be diluted relatively heavilywith water and, in addition, the stock liquors have to be constantly andintensively mixed and circulated to prevent individual components beingdeposited in the feed lines to the points of consumption. Processes suchas these require considerable investment in large mixing vessels and theassociated static mixers and feeders, and also a constant supply ofenergy for the heating and circulation of the stock liquors.

A detergent which meets these requirements is proposed in EP 0 295 525.This detergent is a paste which imposes particular demands on handlingfor the purpose of dosing and mixing with water as solvent. An injectoroperating on the principle of the water jet pump with an integratedshutoff member is proposed in this document for dosing and mixing. Ameasuring arrangement based on conductivity measurements is disclosed asthe dose size detector. A chemical dispenser for dosing chemicalsolutions of unknown concentration or variable concentration inconjunction with a detector based on conductivity measurement and acorresponding process are also described in EP 0 229 038.

The hitherto proposed solutions present difficulties for the shutoffmember integrated in the injector. They are concerned either withshutting off the entry of water into the paste supply line or withshutting off the supply of paste. Hitherto, there has not been asatisfactory shutoff system which provides for controlled dosing andmixing.

3.0 Summary Of The Invention

The technical problem addressed by the present invention is to furtherdevelop a known apparatus and a process for operating this apparatus insuch a way that the supplies of paste-form substances and their solventscan be separately shut off so that dosing of the mixture components inaccordance with the mixing ratios possible in a simple, exact andreproducible manner and with minimal outlay.

In apparatus of the type described above, this problem has been solvedby the fact that the shutoff member is a dual control piston assemblyfor separately closing an opening between the paste supply line and aninjector suction chamber, and an opening between the solvent supply lineand an injector ante-chamber. In addition, the process described abovewhich through the opening of a solvent shutoff member in a feed line forthe solvent under pressure, a dual control piston assembly moves againstcounteracting force and, in doing so, initially opens a connectionbetween a paste feed line and an injector suction chamber. Thereafter, aconnection between a solvent feed line and an injector ante-chamber,results in paste being taken into the injector, which operates on theprinciple of a water jet pump. The paste is mixed with the advancingsolvent and the resulting mixture is injected into a measuring zone inwhich the quantity of paste dissolved in the mixture is determined by aconductivity measuring arrangement and, after a preset dose size hasbeen reached, the solvent shutoff member is closed, after which thepreceding opening sequence takes place in the reverse order for shuttingoff.

The dosing/dispensing arrangement according to the invention has theadvantage that, through the separate shutting off of the paste andsolvent feed lines, controlled dosing taking the exact mixing ratiosinto account is possible with simple means. It is of particularadvantage if, during opening, first the paste feed line and then thesolvent feed line are opened and if, during shutting off, these stepstake place in reverse order. This ensures that the mixing ratios remainthe same over the entire dosing time.

The arrangement of the dual control piston assembly assembly inaccordance with the invention on a common piston plate, include whichthe solvent under pressure is designed to impinge when thedosing/dispensing system is activated, enables a very simple andeffective sequential control to be inexpensively obtained. The use of a2/2 shutoff member, i.e. a switch with only two positions, namely fullyopen and fully closed, has the advantage that the solvent is alwaysunder the pressure favorable to the sequential switching. In conjunctionwith this arrangement, the determination known per se of the dose sizeon the basis of a conductivity measurement affords particular advantagesbecause, together, they provide for very precise dosing.

The design of an outlet pipe for the solvent from the space in which thepiston plate is accommodated as a bypass between that space and themeasuring zone represents an advantageous solution which, with minimaloutlay and without significantly affecting the dosing and mixing result,enables the solvent to be removed from that space so that the dualcontrol piston assembly can be completely closed. Other solutions forremoving the solvent would require very expensive 3/2 fittings in thesolvent feed line and/or expensive connections to a disposal line.

The control system proposed in one particular embodiment readily enablesthe sequences of the individual switching steps to be effectivelycontrolled and monitored. The proposed process or method advantageouslyaffords the possibility of carrying out dosing and mixing by injectorand dose size determination on the basis of conductivity measurement ina form which optimally utilizes the possibilities of these units andcombines them with one another in a simple manner, enabling theinvention to be advantageously put into practice.

The apparatus and method according to the invention are described aboveall with reference to paste-form detergents and their use in washingprocesses after dosing and mixing. In washing processes, water isusually the preferred solvent. However, they are equally suitable forother paste-form chemicals and solvents.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages described above and other advantages are illustrated bythe following description of an embodiment which is shown in theaccompanying drawings, in which like items are identified by the samereference designation, wherein:

FIG. 1 shows the dual control piston assembly in a closed position; and

FIG. 2 shows the dual control piston assembly in an open position.

DETAILED DESCRIPTION OF THE INVENTION

The illustration of an embodiment of the dispenser 1 shows—coming fromthe right—the solvent feed line 8 for the solvent which is normallywater. The solvent arrives under high pressure and is separated from thedispenser 1 by the solvent shutoff member 9. A 2/2 shutoff valve or cockwhich only has two positions, namely fully open and filly closed, hasproved to be of particular advantage for this purpose. If the solventshutoff member 9 is open, the water under pressure impinges on thecontrol piston 6 arranged on the piston plate 15. The piston plate 15 isarranged on a guide plate 18 which is designed for axial displacement inthe cylindrical space 10. The space 10 is watertight. Arranged beneaththe guide plate 18 is a spring 16 against which the guide plate 18 isaxially displaceable.

The water waiting laterally under pressure beneath the injector 2impringes on the piston plate 15 adjacent the arrangement of the piston6 and pushes piston plate 15 downwards. In the embodiment illustrated,the spring 16 is designed in such a way that it is deflected under awater pressure of 2.5 bar. When the piston plate 15 moves downwards, ittakes along the pistons 5 and 6 arranged on it. In the closed position,the piston 5 closes the connection between the paste feed line 7 and theinjector suction chamber 4, while the piston 6 shuts off the connectionbetween the feed line 8 and the injector ante-chamber 3. The length ofthe intervals and, accordingly, the length of the pistons 5 and 6 isselected so that, when the dual control piston assembly 5, 6, 15descends, the connection from the paste feed line 7 to the injectorsuction chamber 4 is the first to be opened. As the piston plate 15continues to descend, the connection from the solvent feed line 8, i.e.the water waiting under pressure, to the injector ante-chamber 3 is thenopened by the piston 6.

By virtue of the 2/2 design of the solvent shutoff member 9, the wateris immediately under full operating pressure, i.e. 2.5 bar in theillustrated embodiment, and is forced through the narrow injector nozzle2. The injector 2 directs water through the cylinder space for thepiston 5 into the injector suction chamber 4 and the co-axial measuringzone 13. The advancing water causes paste to be taken in from the pastefeed line 7, whereby the paste is dissolved and mixed with the water.The resulting mixture is injected into the measuring zone 13 in whichits electrical conductivity is measured by the measuring electrodes 14arranged at intervals in the direction of flow. This measuringarrangement enables the exact amount of paste present in the mixture tobe determined, so that even pastes of unknown concentration or varyingconcentration can be quantitatively determined with considerableprecision. An integrator in a control system (not shown) determines thetotal dose size and, when the preset dose size is reached, gives thecommand to close the system. The transport of the paste mixturedissolved in water flowing through the product line 17 is theninterrupted.

Not that a dosing chamber is provided in fluid communication with thepast feed line 7 and solvent fluid feed line 8. The dosing chamberincludes an inlet or injector suction chamber 4 through which the pasteand the solvent enter, an outlet 17 through which the mixture of pasteand solvent exits for dispensing, and a dose size detector including acoaxial measuring zone 13 for detecting via conductivity measurementelectrodes 14 the presence of a preset dose of solvent and pastetherein.

When the solvent shutoff member 9 closes the solvent feed line 8, thewater under pressure is isolated from the apparatus. The piston plate 15is thus moved upwards by the spring 16 via its guide plate 18. At thesame time, the pistons 5 and 6 move into their cylindrical displacementspaces, first the connection from the solvent feed line 8 to theinjector ante-chamber 3 and then connection from the paste feed line 7to the injector suction chamber 4 being closed. The water displaced intothe injector 2 through the positioning of piston 6 for the injectorantechamber 3 dissolves the paste still present and mixes with anywastewater flowing off through the bypass 12. Since the space 10 iswatertight, the guide plate 18 with the piston plate 15 arranged thereonand the pistons 5 and 6 can only be moved upwards after closure of theopening to the injector ante-chamber 3 when the water still present inthe space 10 can be removed via the bypass 12. The amount of waterflowing through the bypass 12 after closure of the connection to theinjector ante-chamber 3 is so small that it does not significantlyaffect the mixing ratio.

Although various embodiments of the invention have been shown anddescribed, they are not meant to be limiting. Those of skill in the artmay recognize certain modifications to these embodiments, whichmodification are meant to be covered by the spirit and scope of theappended claims.

What is claimed is:
 1. An apparatus for dosing and mixing quantities ofpaste-form substances and a solvent in a preset ratio prior todispensing, said apparatus comprising: a paste feed line for supplyingpaste to said apparatus; a solvent feed line for supplying a solvent tosaid apparatus, said solvent feed line including a solvent shutoffmember for selectively interrupting the flow of the solvent through thesolvent feed line; a dual piston control assembly including a pistonplate adapted for movement between a first position and a secondposition, and first and second pistons each extending from one side ofsaid piston plate; a dosing chamber in fluid communication with thepaste and solvent fluid feed lines, said dosing chamber including aninlet through which the paste and the solvent enter, an outlet throughwhich the mixture of paste and solvent exits for dispensing, and a dosesize detector for detecting via conductivity measurement the presence ofa preset dose of solvent and paste therein; and a first passage fluidlyconnecting the paste feed line with the inlet of the dosing chamberenabling fluid flow therebetween, and a second passage fluidlyconnecting the solvent feed line with the first passage configured forenabling high velocity jet-stream fluid flow therebetween, therebyinducing sufficient mixing between the paste and solvent, said first andsecond passages each being configured for receiving said first andsecond pistons, respectively, as the piston plate moves to the firstposition to close the corresponding fluid flows therethrough.
 2. Dosingapparatus as claimed in claim 1, wherein the first position and secondposition occupied by the piston plate of the dual piston controlassembly include a closed position and an open position, respectively.3. Dosing apparatus as claimed in claim 2, wherein the first and secondpistons and the piston plate of the dual piston control assembly, inmoving from the closed position to the open position, first opens thefirst passage between the paste feed line and the dosing chamber, andthen the second passage between the solvent feed line and the firstpassage and, in moving to the closed position, shuts off thecorresponding first and second passages in reverse order.
 4. Dosingapparatus as claimed in claim 1, further including an injector in fluidconnection between the second passage and the first passage for passinga jet-like stream of solvent into the dosing chamber via the secondpassage.
 5. Dosing apparatus as claimed in claim 4, wherein the dosingchamber further includes a dose size detector having a measuring zonewith a plurality of conductivity measuring electrodes being arranged atintervals in the direction of flow, the measuring zone being arranged insuch a way that it is co-axial with the injector.
 6. Dosing apparatus asclaimed in claim 5, wherein a discharge line for the solvent is a bypassbetween a sealed space containing said first and second pistons arrangedon the piston plate, and the dosing chamber.
 7. Dosing apparatus asclaimed in claim 5, further including a control system which is designedto open the solvent shutoff member, to control the operating sequencesof the dual piston control assembly, to evaluate signals from saidplurality of conductively measuring electrodes, and to close the solventshutoff member when a preset paste dose size is reached.
 8. Dosingapparatus as claimed in claim 7, wherein a discharge line for thesolvent is a bypass between a sealed space containing said first andsecond pistons arranged on the piston plate, and the dosing chamber. 9.Dosing apparatus as claimed in claim 1, wherein the dual piston controlassembly further includes a spring element disposed on one side of saidpiston plate for normally biasing the piston plate into the firstposition.
 10. Dosing apparatus as claimed in claim 9, wherein the firstand second pistons arranged on the piston plate reside in a sealedspace, the piston plate—after opening of the shutoff member in thesolvent feed line—being exposed to the solvent under pressure movesagainst the force of the spring element to the second position, thesealed space including a connection to a discharge line for the solvent.11. Dosing apparatus as claimed in claim 10, wherein the discharge linefor the solvent is a bypass between the sealed space and the dosingchamber.
 12. Dosing apparatus as claimed in claim 10, wherein thesolvent shutoff member has only two states of operation, namely an openstate and a closed state.
 13. Dosing apparatus as claimed in claim 12,wherein the discharge line for the solvent is a bypass between thesealed space and the dosing chamber.
 14. A process for dosing paste-formsubstances and for mixing them with a solvent, said process comprising:deactivating a solvent shutoff member located in a pressurized solventfeed line for supplying a solvent; moving a dual control piston assemblyfrom a closed position to an open position in response to the pressureexerted by the supplied solvent impinging on said dual control pistonassembly; opening a first passage fluidly connecting a paste feed linefor supplying a paste to a dosing chamber with an outlet for dispensinga solvent/paste mixture, as the dual control piston assembly moves tothe open position; opening a second passage fluidly connecting thesolvent feed line to the first passage for directing a jet stream of thesolvent into the first passage for at least substantial mixing with thesupplied paste; directing the resulting solvent/paste mixture into thedosing chamber, wherein said dosing chamber further includes aconductivity measuring apparatus; measuring the dose size of thesolvent/paste mixture by said measuring apparatus through gauging theconductivity of the solvent/paste mixture; detecting a preset dose sizeof the solvent/paste mixture; activating the solvent shutoff member forinterrupting the supply of solvent; and moving the dual control pistonassembly from the open position to the closed position in response tothe absence of the solvent impinging on the dual control pistonassembly, wherein the preceding passage opening steps takes place inreverse order for closing off the paste and solvent feed lines from thedosing chamber.